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. W. F. LUHNOW PHONOGRAPH Filed Jan. 5, 1920 W i W n M 2 0 Patented den. 29, 1924.

NlTED STATES WALTER F. LUHNOW, OF OAK PARK, ILLINOIS.

PHONOGRAPH.

Application filed January 5, 1920. Serial No. 349,443.

To all whom it may concern Be it known that I, WALTER F. LUHNow, a citizen of the United States of America, and a resident of Oak Park, county of Cook, and State of Illinois, have invented certain new and useful Improvements in Phonographs, of which the following is a specification.

This invention relates mainly to phonographs, and especially to the amplifying passageway and chamber thereof and to the atmospheric conditions therein.

I have found by experiments with phonographic and other sound apparatus, and by extended investigation, that the condition of the air or other gas constituting the soundconducting medium has a marked influence on the sound transmitted, respecting its volume, timbre, and other qualities. The more important factors determining the essential qualities of the sound reproduced appear to be temperature, humidity, attenuation, and circulation. Good sound reproduction and transmission appear to be enhanced by warming and drying the air in some degree and thereby attenuating it, and by mildly circulating same in the amplifying chamber, as will be more fully explained.

The main objects of the invention are to provide a method and means for improv ing the atmospheric conditions in a phonographic apparatus, and particularly in the sound box or amplifying member; to provide means for attempering the air in the sound passageway and amplifying chamber; to provide means for heating the air therein; to provide for circulation thereof; and to provide an improved form of cabinet and chamber and an improved arrangement of apparatus therein adapted to facilitate carrying out and effecting the objects above set forth.

Illustrative embodiments of this invention are shown in the accompanying drawings, in which Fig. 1 is a vertical section of a novel form of phonographic instrument through the axis of the throat of the amplifying chamher, which in this instance is near the center and is disposed to throw the sound directly upward through a horizontally disposed heater.

Fig. 2 is a similar section of a modified form of cabinet and arrangement of apparatus in which the throat of the amplifying chamber is adjacent to the back side of the cabinet and itself is formed to deflect the sound from a horizontal rearward direction to an upward direction, and the heater element is disposed in a nearly vertical position rather than horizontal.

In the construction shown in Fig. l, the cabinet 1 is of upright character adapted to stand on the floor and is provided in its upper part with an upwardly flaring amplifying chamber 2 beneath which provision is made for mounting the record 3, reproducer arm 4, and associated parts, as will be understood. Said arm is angular in shape and includes a vertical part and a horizontal part. The vertical arm is dependingly supported pivotally at 5 to swing on its vertical axis, and the horizontal arm swings over the position occupied by the record plate. Said horizontal arm is jointed at 6 so that its outerpart 6', on which the reproducer 7 is mounted, may swing upwardly to clear the record when not in use, as usual in such devices.

Said chamber 2 is substantially conoidal in shape from the lowermost point or sound inlet port at 5, upward to the top rim 8 of the cabinet, and is preferably enclosed by a light, thin and preferably foraminous or reticulated dome-shaped roof or cover 9, which may be in the form of silk on a suitable framework, or it may be of a certain ornamental material commonly used for lamp shades, as will be understood.

In order to attemper the air, means 10 are provided in the lower part of the amplifying chamber for heating the air adjacent to the point of connection of the reproducer arm at 5, said heating means preferably being in the form of an electrical heater element composed of resistance wires suitably disposed to heat the surrounding air as understood in the art. Said heater is connected by wires 11 leading to a sourceof current 12, and the circuit is controlled by a switch 13.

Means are provided for circulation of air. as by convection. In order to provide for this, intake apertures 14 are provided at the upper edges of the flaring chamber walls 2 and the heated air, rising centrally, circulates and gradually escapes through the covering 9 of said chamber.

In the construction shown in Fig. 2, the general design is somewhat similar, but the downward apex 15 of the conoidal amplifying chamber 16 is adjacent to the rear wall 17 instead of being central. Moreover, the

straight arm 18 swings horizontally on a suitable support at 19 opposite the inclined heater 20. In this instance the air is admitted through an intake aperture 21 in the back of the cabinet, behind said heater, so that the incoming air has to pass through the heater, as indicated by arrows. Thence it circulates upward and throughout the chamber 16 gradually escapes through the roof material 22 as in Fig. 1. The air inlet 2%{is preferably screened by fabric 23 or the li e.

The heater receives its current from the source 24 through wires 25 and switch 26.

Although but two specific embodiments of this invention are herein shown and described, it is to be understood that some of the details of the constructions shown may be altered or omitted without departing apertures at substantially its lowermost part, sound producing means communicatmg with one of said apertures and a heat generator disposed across the face of the other in non-obstructive relation adapted to produce an upward current of air from the latter aperture, the upper part of said chamber being adapted to permit discharge of the ascending air.

Signed at Chicago this 23rd day of December, 1919.

WALTER F. LUHNOW. 

